Plumbing fixtures such as sinks that have faucets for supplying water, conventionally use a pop-up type drain valve assembly for controlling the flow of water through the drain. This type of assembly is provided with a manually operable control mechanism for raising and lowering a drain plug to open and close the drain. The control mechanism is normally comprised of a plunger rod connected to a ball lever which pivots on a fulcrum to translate the downward force applied to the plunger rod into an upward force for lifting the drain plug and opening the drain. When an upward force is applied to the plunger rod, the ball lever pivots in the opposite direction to allow the drain plug to drop by means of gravity to close the drain.
The prior art has provided a number of different arrangements for pop-up type drain valve assemblies. One such arrangement is disclosed in U.S. Pat. No. 3,731,326 issued to Politz on May 8, 1973. Politz discloses a ball lever having a plastic cover and ball member seated on one end of the rod 21 that prevents corrosion.
Another arrangement is disclosed in U.S. Pat No. 3,419,919 issued to Stayner on Jan. 7, 1969. Stayner discloses a plastic hinged ball lever which is connected by means of a set screw to a plunger rod that extends through a transverse bore in the lever.